1. Technical Field
The present invention relates to an electronic structure that includes a metallic interlocking structure for bonding a metallic plating to metal surface, and to a method of forming the electronic structure.
2. Related Art
In plating copper onto a microvia in the form of a blind via, electroless plating of copper is typically used to coat the sidewalls and the metallic bottom surface of the blind via to provide electrical commoning for subsequent copper electroplating on the electroless coat of copper. Reliability of a copper-plated blind via depends on an adhesive bond between the plated copper and the metallic bottom surface of the blind via. If the adhesive bond is weak, the copper plating may separate from the bottom metallic surface during periods of thermal stress testing or during sustained operation in the field. Similar reliability concerns exist for other geometries, such as for copper plating in a channel over a metallic surface at the bottom of the channel.
Thus a method is needed to provide a strong bond between plated copper and a metallic surface onto which the copper is plated.
The present invention provides a method for forming a structure, comprising the steps of:
providing a substrate having a metallic sheet interior to a dielectric layer, said metallic sheet including a metal;
laser drilling a blind opening through the dielectric layer and partially through the metallic sheet, said laser drilling creating a metallic protrusion that is integral with a portion of the metallic sheet, said metallic protrusion having metallic strands such that each metallic strand includes the metal and at least one constituent element from the dielectric layer; and
etching a portion of the metallic protrusion to form a metallic interlocking structure that is integral with the portion of the metallic sheet and projects into the blind opening.
The present invention provides a structure, comprising:
a substrate having a metallic sheet interior to a dielectric layer, said metallic sheet including a metal;
a blind opening through the dielectric layer and partially through the metallic sheet;
a metallic interlocking structure coupled to a blind surface of the blind opening and projecting into the blind opening, wherein the metallic interlocking structure is integral with a portion of the metallic sheet, wherein the metallic interlocking structure includes metallic fibers, and wherein each metallic fiber has a curved geometry and has its own unique composition that includes material selected from the group consisting of the metal, at least one constituent element of the dielectric layer, and combinations thereof.
The present invention has the advantage of provide a strong bond between a metallic plating, such as plated copper, and a metal surface which receives the metallic plating, so as to significantly improve the reliability of the plating bond.
The present invention has the advantage of providing a plating bond that is strong enough to allows metal surfaces to be plated even if such metal surfaces are difficult or impossible to be plated without the present invention.
The present invention has the advantage of forming a reliable plating in a variety of geometries, including a plated blind via and a plated channel.